"It was very serious offending involving gross dishonesty and a breach of trust that required significant planning and forethought," Judge Barbara Cotterell told the court in her sentencing remarks.

Police find cash, jewellery, gold bars and Rolex in employee's home

Police said he admitted to pocketing $600,000 and they found jewellery, gold bars, high-end cars, a Rolex watch and other luxury items as well as cash at his home.

But they said there was an additional $600,000 in bank deposits that could not be explained.

While the court heard Jackson had once had a gambling problem, Judge Cotterell said that was not the motivation for his offending.

She said it was "to enable you to exhibit outward signs of wealth and prestige".

The court heard Jackson had twice failed to turn up for court trials in September 2013 and then in October 2014, but eventually turned himself in 2015, pleading guilty to benefit from the proceeds of suspected crimes and attempted theft.

But Judge Cotterell noted that Jackson now suffered depression and his mental health would have worsened had his jail term been extended.

The court heard he had made a strong contribution to the RBA and public service, assisting the Department of Foreign Affairs and Trade to develop Australia's biometric passports as well as developing several patented items.